The present invention relates to a device for supplying a machine working on a web of material in a stopped position. More particularly but not exclusively, the invention is concerned with supplying a flat cutting press.
In a flat cutting press which ensures a cyclic cut-out of a continuous web printed or not, of a material such as cardboard, this web is generally delivered upstream, in continuous manner, from a reel. As the flat cutting press is a machine which necessitates a momentary stop of the advance of the web of material, during the cutting operation, an accumulation is produced of the material to be cut, upstream of the cutting press, due to the continuous supply. In order to be able to accumulate the length of web supplied upstream, whilst a downstream part of this web is stopped in the flat cutting press, various devices have already been designed for storing the excess length of web in the form of a loop of variable length. This loop lengthens the cutting press is inoperative and it shortens as soon as supply of the cutting press resumes for a subsequent cutting operation, these operations being carried out cyclically. The fact of not holding the web, results in defective positioning of the web as soon as the speed of operation increases.
In order to overcome this drawback, devices avoiding the formation of a free loop, with the aid of a compensating mechanism comprises a mobile roller taking up this loop, have been envisaged. A particular device of this type is described in Patent FR-A-2 408 538 and employs a solution introducing a minimum slide of the web over the roller fast with the compensating mechanism, for a determined cut-out format but this slide becomes considerable if the cut out format varies. Furthermore, such a device requires the machine to stop in order to be adjusted, it comprises a complex mechanism and a double control on each side. As a result, such a device is relatively complex and inconvenient to carry out.